Towards an understanding of the age and origin of mesothermal gold mineralisation in the Etheridge Goldfield, Georgetown region, north Queensland

Small mesothermal vein quam-gold-base-metal sulfide deposits from which some 20 t of Au-Ag bullion have been extracted, are the most common gold deposits in the Georgetown region of north Queensland-several hundred were mined or prospected between 1870 and 1950. These deposits are mostly hosted by Proterozoic granitic and metamorphic rocks and are similar to the much larger Charters Towers deposits such as Day Dawn and Brilliant, and in some respects to the Motherlode deposits of California. The largest deposit in the region-Kidston (> 138 t of Au and Ag since 1985)- is substantially different. It is hosted by sheeted quartz veins and cavities in brecciated Silurian granite and Proterozoic metamorphics above nested high-level Carboniferous intrusives associated with a nearby cauldron subsidence structure. This paper provides new information (K-Ar and Rb-Sr isotopic ages, preliminary oxygen isotope and fluid-inclusion data) from some of the mesothermal deposits and compares it with the Kidston deposit. All six dated mesothermal deposits have Siluro-Devonian (about 425 to 400 Ma) ages. All nine of such deposits analysed have delta(18)O quartz values in the range 8.4 to 15.7 parts per thousand, Fluid-inclusion data indicate homogenisation temperatures in the range 230-350 degrees C. This information, and a re-interpretation of the spatial relationships of the deposits with various elements of the updated regional geology, is used to develop a preliminary metallogenic model of the mesothermal Etheridge Goldfield. The model indicates how the majority of deposits may have formed from hydrothermal systems initiated during the emplacement of granitic batholiths that were possibly, but not clearly, associated with Early Palaeozoic subduction, and that these fluid systems were dominated by substantially modified meteoric and/or magmatic fluids. The large Kidston deposit and a few small relatives are of Carboniferous age and formed more directly from magmatic systems much closer to the surface.

Suicide and recency of health care contacts - A systematic review

Background Many countries have set targets for suicide reduction, and suggested that mental health care providers and general practitioners have a key role to play. Method Asystematic review of the literature. Results Among those in the general population who commit suicide, up to 41% may have contact with psychiatric inpatient care in the year prior to death and up-to 9% may commit suicide within one day of discharge. The corresponding figures are I I and 4% for community-based psychiatric care and 83 and 20% for general practitioners. Conclusions Among those who die by suicide. contact with health services is common before death. This is a necessary but not sufficient condition for clinicians to intervene. More work is needed to determine whether these people show characteristic patterns of care and/or particular risk factors which would enable a targeted approach to be developed to assist clinicians in detecting and managing high-risk patients.

A qualitative study of Australian GPs' attitudes and practices in the diagnosis and management of attention-deficit/hyperactivity disorder (ADHD)

Background. The importance of general practice involvement in the care of attention-deficit/hyperactivity disorder (ADHD) is increasing due to the rising numbers of patients who present with the disorder. It has been suggested by consensus bodies that GPs should be identifying and referring patients at the severe end of the ADHD spectrum and managing those with less severe symptoms. However, GPs' views of their role in ADHD care are unknown. Objective. Our aim was to explore the attitudes and practices of Australian GPs towards the diagnosis and management of ADHD. Methods. We conducted a series of focus groups to explore GPs' beliefs regarding the causes of ADHD, their perceived role in ADHD diagnosis and management and their views on the role of behaviour therapies and pharmacotherapies in ADHD management. The subjects were 28 GPs in six focus groups. Results. GPs in this study did not want to be the primary providers of care for patients with ADHD. Participants indicated a preference to refer the patient to medical specialists for diagnosis and treatment of ADHD, and expressed low levels of interest in becoming highly involved in ADHD care. Concerns about overdiagnosis and misdiagnosis of the disorder, diagnostic complexity, time constraints, insufficient education and training about the disorder, and concerns regarding misuse and diversion of stimulant medications were the reasons cited for their lack of willingness. Conclusions. The Australian GPs in this study identify a role for themselves in ADHD care which is largely supportive in nature, and involves close liaison with specialist services.

Stem cells in the aetiopathogenesis and therapy of rheumatic disease

Animal models of autoimmune disease and case reports of patients with these diseases who have been involved in bone marrow transplants have provided important data implicating the haemopoietic stem cell in rheumatic disease pathogenesis. Animal and human examples exist for both cure and transfer of rheumatoid arthritis, systemic lupus erythematosus (SLE) and other organ-specific diseases using allogeneic haemopoietic stem cell transplantation. This would suggest that the stem cell in these diseases is abnormal and could be cured by replacement of a normal stem cell although more in vitro data are required in this area. Given the morbidity and increased mortality in some patients with severe autoimmune diseases and the increasing safety of autologous haemopoietic stem cell transplantation (HSCT), pilot studies have been conducted using HSCT in rheumatic diseases. It is still unclear whether an autologous graft will cure these diseases but significant remissions have been obtained which have provided important data for the design of randomized trials of HSCT versus more conventional therapy. Several trials are now open to accrual under the auspices of the European Bone Marrow Transplant Group/European League Against Rheumatism (EBMT/EULAR) registry. Future clinical and laboratory research will need to document the abnormalities of the stem cell of a rheumatic patient because new therapies based on gene therapy or stem cell differentiation could be apllied to these diseases. With increasing safety of allogeneic HSCT it is not unreasonable to predict cure of some rheumatic diseases in the near future.

The nature and evolution of the association among digeneans, molluscs and fishes

Patterns of association of digenean families and their mollusc and vertebrate hosts are assessed by way of a new database containing information on over 1000 species of digeneans for lift-cycles and over 5000 species from fishes. Analysis of the distribution of digenean families in molluscs suggests that the group was associated primitively with gastropods and that infection of polychaetes, bivalves and scaphopods are all the results of host-switching. For the vertebrates. infections of agnathans and chondrichthyans are apparently the result of host-switching from teleosts. For digenean families the ratio of orders of fishes infected to superfamilies of molluscs infected ranges from 0.5 (Mesometridae) to 16 (Bivesiculidae) and has a mean of 5.6. Individual patterns of host association of 13 dipenean families and superfamilies are reviewed. Two, Bucephalidae and Sanguinicolidae. are exceptional in infecting a range of first intermediate hosts qualitatively as broad as their range of definitive hosts. No well-studied taxon shows narrower association with vertebrate than with mollusc clades. The range of definitive hosts of digeneans is characteristically defined by eco-physiological similarity rather than phylogenetic relationship. The range of associations of digenean families with mollusc taxa is generally much narrower. These data are considered in the light of ideas about the significance of different forms of host association. If Manter's Second Rule (the longer the association with a host group, the mure pronounced the specificity exhibited by the parasite group) is invoked, then the data may suggest that the Digenea first parasitised molluscs before adopting vertebrate hosts. This interpretation is consistent with most previous ideas about the evolution of the Digenea but contrary to current interpretations based on the monophyly of the Neodermata. The basis of Manter's Second Rule is. however, considered too flimsy for this interpretation to be robust. Problems of the inference of the evolution of patterns of parasitism in the Neodermata al-e discussed and considered so intractable that the truth may be presently unknowable. (C) 2001 Australian Society for Parasitology Inc. Published by Elsevier Science Ltd. All rights reserved.

Binocular rivalry and the cerebral hemispheres with a note on the correlates and constitution of visual consciousness

In addressing the scientific study of consciousness, Crick and Koch state, "It is probable that at any moment some active neuronal processes in your head correlate with consciousness, while others do not: what is the difference between them?" (1998, p. 97). Evidence from electrophysiological and brain-imaging studies of binocular rivalry supports the premise of this statement and answers to some extent, the question posed. I discuss these recent developments and outline the rationale and experimental evidence for the interhemispheric switch hypothesis of perceptual rivalry. According to this model, the perceptual alternations of rivalry reflect hemispheric alternations, suggesting that visual consciousness of rivalling stimuli may be unihemispheric at any one time (Miller et al., 2000). However, in this paper, I suggest that interhemispheric switching could involve alternating unihemispheric attentional selection of neuronal processes for access to visual consciousness. On this view, visual consciousness during rivalry could be bihemispheric because the processes constitutive of attentional selection may be distinct from those constitutive of visual consciousness. This is a special case of the important distinction between the neuronal correlates and constitution of visual consciousness.

Telehealth and the diagnosis and management of cardiac disease

The financial and personal burden of chronic cardiac disease is high. Costs are likely to increase over the next few decades. Promising applications of telehealth have appeared in the diagnosis and management of cardiac disease and there are indications that telehealth services can improve the management of chronic cardiac disease as well as extend services to remote and rural populations. Telehealth has been applied to the capture of symptoms of cardiac disease with electrocardiography and echocardiography, to the management and rehabilitation of recently discharged patients, and in peer-to-peer consultation where remote expertise can facilitate diagnosis. Telehealth promises cost reductions in service delivery, although there is a need for properly controlled cost-effectiveness trials to underpin telehealth with a firm evidence base.

Pro re nata medication for psychoses: the knowledge and beliefs of doctors and nurses

Objective: To examine the knowledge and beliefs of doctors and nurses in inpatient psychiatric units about pro re nata (PRN) (as needed) medications for psychotic disorders. Methods: Medical (n = 44) and nursing (n = 80) staff in two metropolitan public hospital units completed a structured questionnaire about their use of PRN psychotropic medications on one occasion during the four months from March-June 1999. Results: Nurses selected more indications for PRN antipsychotics than doctors (3.49 vs 2.72, p < 0.05), whereas doctors selected more indications for PRN benzodiazepines (3.77 vs 3.19, p < 0.05). The groups did not differ in the number of selected indications for using anticholinergics. For agitation, the majority of nurses viewed both benzodiazepines (56%) and antipsychotics (86%) as effective, with 60% preferring an antipsychotic. For the acute control of psychotic symptoms, 99% of nurses believed antipsychotics were effective and 58% benzodiazepines, with 87% preferring an antipsychotic. A large majority of doctors viewed both PRN benzodiazepines, 94% ,and antipsychotics, 81%, as effective for agitation, and 55% preferred to use a benzodiazepine. For psychotic symptoms, 80% believed PRN antipsychotics were effective, but only 32% viewed benzodiazepines as effective, and 64% preferred to use an antipsychotic. Nursing staff identified more non-pharmacological techniques for managing both agitation and psychotic symptoms and reported using these more often than doctors. Junior staff, both nursing and medical, had less knowledge of non-pharmacological alternatives to PRN medication than senior staff. Conclusions: Disparities existed between doctors and nurses views on the indications for PRN medication in the acute management of psychoses, thus it is important for doctors to specify indications when writing PRN prescriptions. Despite evidence for the safety and effectiveness of benzodiazepines, there was widespread reluctance to use them as PRN medication in acute psychoses. Beliefs of some staff about PRN medications were at odds with the known properties of these medicines. Educational interventions for both nurses and doctors are required to achieve best practice in PRN medication.